The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, power supply controllers often used zero crossing detectors to determine when current through an inductor of the power supply was reaching a zero crossing in order to control the power switches of the power system. Switching the power switches at the zero crossing improved the efficiency of the power supply controller. Typically, a comparator compared a current sense signal to a reference signal in order to determine when the current sense signal was approaching the zero crossing of the signal. However, the comparators had variations that limited the accuracy of the comparators and reduced the efficiency of the power supply system. The variations typically resulted from semiconductor processing variations and temperature variations. In battery-powered operations, the variations caused reduced power efficiency and reduced the length of time the equipment could be operated from the battery.
Accordingly, it is desirable to have a zero crossing detector that has improved accuracy and that more accurately detects the zero crossing of a sense signal.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor.